When attaching a bone plate to a bone of a patient, medical professionals need to perform drilling, tapping, and/or screwing steps. When performing these tasks, it is often beneficial for the hole, threads, or screw to be straight, for the drilling, tapping, and/or screwing tool to reduce excess lateral pressure to the bone that could weaken or break the bone around the hole, for the medical professional to know a depth of the drill bit within a patient, and for the medical professional to control the maximum depth of the drill bit within the patient. For example, when drilling, tapping, or screwing in order to attach a plate to underlying bone, the holes should be straight into the bone at an angle that promotes solid attachment and to a precise, controlled depth.
Early solutions for attaching a plate to underlying bone involved drilling, tapping, and/or screwing without any guide. Without a guide, the surgeon had to maintain a particularly steady hand and had to rely on judging the angle of entry and depth with the naked eye. Eventual solutions involved drilling and tapping a hole through a guide, then removing the guide and screwing the screw into the hole by hand or without the aid of a guide.